Brain, Spinal Cord, and Nerve Disorders - Merck Manuals Consumer Version

Biology of the Nervous System

The nervous system has two distinct parts: the central nervous system (the brain and spinal cord) and the peripheral nervous system (the nerves outside the brain and spinal cord).
Symptoms of Brain, Spinal Cord, and Nerve Disorders

Disorders that affect the brain, spinal cord, and nerves are called neurologic disorders.
Diagnosis of Brain, Spinal Cord, and Nerve Disorders

The nervous system consists of the brain, spinal cord, and nerves that connect the brain and spinal cord to the rest of the body ( peripheral nerves).
Autonomic Nervous System Disorders

The autonomic nervous system regulates certain body processes, such as blood pressure and the rate of breathing. This system works automatically (autonomously), without a person’s conscious effort.
Brain Dysfunction

Brain damage can cause many types of dysfunction. Such dysfunction ranges from complete loss of consciousness (as occurs in a coma), to disorientation and an inability to pay attention (as occurs in delirium), to impairment of one or several of the many specific functions that contribute to conscious experience.
Brain Infections

Infections of the brain can be caused by viruses, bacteria, fungi, or, occasionally, protozoa or parasites. Another group of brain disorders, called spongiform encephalopathies, are caused by abnormal proteins called prions.
Coma and Impaired Consciousness

Consciousness has two parts:
Cranial Nerve Disorders

Twelve pairs of nerves—the cranial nerves—lead directly from the brain to various parts of the head, neck, and trunk. Some of the cranial nerves are involved in the special senses (such as seeing, hearing, and taste), and others control muscles in the face or regulate glands. The nerves are named and numbered (according to their location, from the front of the brain to the back).
Craniocervical Junction Disorders

Craniocervical junction disorders are abnormalities of the bones that join the head and neck. (Cranio- means skull, and cervical means neck.)
- Craniocervical Junction Disorders
  - Causes
    - Present at birth
    - Acquired
  - Symptoms
  - Diagnosis
  - Treatment
Delirium and Dementia

Delirium and dementia are the most common causes of mental (cognitive) dysfunction—the inability to acquire, retain, and use knowledge normally.
Headaches

A headache is pain in any part of the head, including the scalp, upper neck, face, and interior of the head. Headaches are one of the most common reasons people visit a doctor.
Meningitis

Meningitis is inflammation of the layers of tissue that cover the brain and spinal cord (meninges) and of the fluid-filled space between the meninges (subarachnoid space).
Movement Disorders

Every body movement, from raising a hand to smiling, involves a complex interaction between the central nervous system (brain and spinal cord), nerves, and muscles. Damage to or malfunction of any of these components may result in a movement disorder.
Multiple Sclerosis (MS) and Related Disorders

Most nerve fibers inside and outside the brain are wrapped with many layers of tissue composed of a fat (lipoprotein) called myelin. These layers form the myelin sheath. Much like the insulation around an electrical wire, the myelin sheath enables nerve signals (electrical impulses) to be conducted along the nerve fiber with speed and accuracy. When the myelin sheath is damaged, nerves do not conduct electrical impulses normally. Sometimes the nerve fibers are also damaged.
Pain

Pain is an unpleasant sensation signaling actual or possible injury.
Peripheral Nerve and Related Disorders

The peripheral nervous system refers to the parts of the nervous system that are outside the central nervous system, that is, those outside the brain and spinal cord.
Prion Diseases

Prion diseases are rare progressive, fatal, and currently untreatable degenerative disorders of the brain (and rarely of other organs) that result when a protein changes into an abnormal form called prion.
Seizure Disorders

In seizure disorders, the brain's electrical activity is periodically disturbed, resulting in some degree of temporary brain dysfunction.
- Seizure Disorders
Sleep Disorders

Sleep is necessary for survival and good health, but why sleep is needed and exactly how it benefits people are not fully understood. One of sleep's benefits is its restorative effect on people's ability to function normally during the daytime.
Spinal Cord Disorders

Spinal cord disorders can cause permanent severe problems, such as paralysis or impaired bladder and bowel control ( urinary incontinence and fecal incontinence). Sometimes these problems can be avoided or minimized if evaluation and treatment are done quickly.
Stroke

A stroke occurs when an artery to the brain becomes blocked or ruptures, resulting in death of an area of brain tissue due to loss of its blood supply (cerebral infarction). Symptoms occur suddenly.
Tumors of the Nervous System

A tumor is an abnormal growth, whether noncancerous (benign) or cancerous (malignant). In many parts of the body, a noncancerous tumor causes few or no problems. However, if any growth or mass in the brain ( brain tumor) or spinal cord ( spinal tumor) is getting larger, it can cause considerable damage because the structures that contain the brain (the skull) and spinal cord (the spine) cannot expand to make room for any increase in their contents.